Appendix IIL 935 been thus treated from end to end by Prof. Weighton, and by Mr. Leavenworth, and is here given in Fig. 888. Commencing at A with the heat in the coal as roo % we find some 4 % of this lost MCOAL 7?7rfrrr/T) 2.6-6 9M//// a 25-6 fltTl7}}j -6 < 8*** I9-65-- q -i-t ffivyMZ^rtft, "mfr7ffifai0 I \ <c -QTTfM- flSSOLC r'2S — . fOO - TOTAL 22 26 172.6 = 2^1 .—68- COAL GRATE BOILER PIPE DROP CYLINDER SHArr PROPELLER FROM BOILER rURNACE TO <$H/P PROPELLER at the grate B due to incomplete combustion or dilution. A further and very great loss occurs in the boiler at c on account of heat passing up the funnel, leaving us with only 73 % of the original heat to go to the steam pipe. A slight loss at D is caused by radiation and condensation in the steam pipe, and 72*27 % is given to the engine as dry steam. Now comes the great unavoid- able natural loss on account of unavailability, present in all prime movers, whether driven by heat, wind, or water, so that the cylinder could not possibly give out more than '27 % of the steam- pipe energy. On this amount, however, there is the loss by initial condensation, which is very large, so that only 12*27 % of the coal energy is ' indicated.' The final losses are the friction of the engine and propeller shaft, and the slip of the propeller, so that the ship is moved forward with only "0726% of the original coal energy, supposing all the heat units to be available. It does not appear, however, that the cylinder should be specially debited with the loss by unavailability, and more probably the best way is to deduct it from the coal energy in the first place.